There are devices known in the related art that reduce the engine speed to a predetermined rotation rate as an operating lever is shifted to a neutral position (see, for instance, patent reference literature 1). Such a device includes a lock mechanism for locking the operating lever at the neutral position, and as the operating lever is moved to the neutral position while the lock mechanism is in a released state, it executes control so as to adjust the engine speed to the predetermined rotation rate. While the lock mechanism is in an engaged state, it executes control so as to adjust the engine speed to a rotation rate (hereafter referred to as a low idle rotation rate) lower than the predetermined rotation rate. The low idle rotation rate, which represents an engine speed achieved by setting the engine accelerator position slightly above the idling position, is the minimum rotation rate at which the engine will not stall when a hydraulic actuator is driven.
Patent Reference Literature 1: Japanese Patent Publication No. 3073896